Prior to the present invention it has been known to manufacture brake shoe stock by first cutting or "blanking" a brake shoe blank from the appropriate steel strip, then abrading the surface as in a grit blast tumbling device, followed by application of a phenol-formaldehyde resin or "glue" to provide adhesion for the pad or lining material. An uncut pre-glued brake shoe stock has not been commercially prepared because of the difficulty of handling coils of the gauge or thickness required for brake shoes, i.e. at least 0.12 inch thick and commonly up to 0.25 inch thick. Continuous coil coating treatment lines for steel strip of thicknesses commonly used for brake shoes--0.123 and 0.187 through 0.25 inch--are not readily available and accordingly the manufacture of finished brake shoes with pads or lining materials has been developed based on the treatment and handling of individual brake shoes rather than the preparation of a brake shoe stock from which the shoe may be cut, sheared or blanked.
Brake shoes for automobiles which are first cut or stamped from the unglued sheet and then treated tend to be somewhat deformed because of the asymmetrical effects of the tumbling abrading treatment to which they are commonly subjected, and tend not to retain an appropriate amount of "glue", adhesive or phenolic resin, in areas which are deformed during stamping and abrading. The uneven application of the resin will cause blistering of the resin on curing, voids in the application of the resin, and other erratic effects.
Continuous coil coating lines have been used in the past for many purposes. Continuous steel coil coating lines have been used for phosphate treatment, oiling, polishing, and the application of various permanent coatings such as paints, for example. So far as we are aware, however, they have not been adapted to the particular problem of making pre-glued brake shoe stock, which requires a thick gauge as herein described.